A Jewish woman older than twelve years and one day must stand over her as she immerses, to see that none of the hair of her head remains floating above the water’s surface.

The Shulchan Aruch goes on to explain that if she does not have someone to observe her tevilah, it is still possible to immerse, so long as she takes steps, such as using a loose hairnet, to ensure that her hair is completely submerged.

In other words, it is a halachic requirement. However, when the requirement cannot be satisfied (or after the fact), an immersion may still be valid if other steps are taken.

For a more detailed discussion, including the source in the original Hebrew, please see our blog post “Does the Mikveh Attendant Need to Watch Me Immerse?”

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